PURPOSE: To take out the target image data by registering the image data without limiting the method of retrieval and classifying the data from various points of view in accordance with the purpose of a user at the time of retrieving.
CONSTITUTION: This device has a feature extracting part 10 to extract the high dimensional feature quantity from the image of image data, a data storing part 12 to register and control the high dimensional, for example, 25-dimension feature quantity obtained by the feature extracting part 10 by combining with the corresponding image data, a feature converting part 14 to pull out the high dimensional feature quantity from the data storing part 12 and convert it to the low dimensional, for example, 2-dimension feature quantity and a displaying part 16 to display the distribution of the converted low dimensional feature quantity. The user, while the user watches the displaying part 16, instructs the conversion through a user instructing part 18 of a keyboard, a mouse, etc., to the feature converting part 14. From the user instructing part 18, the conversion is instructed, for example, at the time of converting to 2 dimension, the icon (image reduced data) as the 2 dimensional feature quantity is displayed at the displaying part 16. By changing the 2 dimensional feature quantity, the icon corresponding to the feature quantity is successively displayed at the displaying part 16.